Merge "Allocate networks in the background"

4 files changed, 143 insertions, 19 deletions

diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index 8a2ddf877..2390eb3c3 100755
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -959,6 +959,9 @@ class ComputeManager(manager.SchedulerDependentManager):
         except exception.InstanceNotFound:
             # the instance got deleted during the spawn
             with excutils.save_and_reraise_exception():
+                # Make sure the async call finishes
+                if network_info is not None:
+                    network_info.wait(do_raise=False)
                 try:
                     self._deallocate_network(context, instance)
                 except Exception:
@@ -966,6 +969,10 @@ class ComputeManager(manager.SchedulerDependentManager):
                             'for deleted instance')
                     LOG.exception(msg, instance=instance)
         except exception.UnexpectedTaskStateError as e:
+            exc_info = sys.exc_info()
+            # Make sure the async call finishes
+            if network_info is not None:
+                network_info.wait(do_raise=False)
             actual_task_state = e.kwargs.get('actual', None)
             if actual_task_state == 'deleting':
                 msg = _('Instance was deleted during spawn.')
@@ -973,10 +980,13 @@ class ComputeManager(manager.SchedulerDependentManager):
                 raise exception.BuildAbortException(
                         instance_uuid=instance['uuid'], reason=msg)
             else:
-                raise
+                raise exc_info[0], exc_info[1], exc_info[2]
         except Exception:
             exc_info = sys.exc_info()
             # try to re-schedule instance:
+            # Make sure the async call finishes
+            if network_info is not None:
+                network_info.wait(do_raise=False)
             rescheduled = self._reschedule_or_error(context, instance,
                     exc_info, requested_networks, admin_password,
                     injected_files_orig, is_first_time, request_spec,
@@ -1111,29 +1121,37 @@ class ComputeManager(manager.SchedulerDependentManager):
 
     def _allocate_network(self, context, instance, requested_networks, macs,
                           security_groups):
-        """Allocate networks for an instance and return the network info."""
+        """Start network allocation asynchronously.  Return an instance
+        of NetworkInfoAsyncWrapper that can be used to retrieve the
+        allocated networks when the operation has finished.
+        """
+        # NOTE(comstud): Since we're allocating networks asynchronously,
+        # this task state has little meaning, as we won't be in this
+        # state for very long.
         instance = self._instance_update(context, instance['uuid'],
                                          vm_state=vm_states.BUILDING,
                                          task_state=task_states.NETWORKING,
                                          expected_task_state=None)
         is_vpn = pipelib.is_vpn_image(instance['image_ref'])
-        try:
-            # allocate and get network info
-            network_info = self.network_api.allocate_for_instance(
-                                context, instance, vpn=is_vpn,
-                                requested_networks=requested_networks,
-                                macs=macs,
-                                conductor_api=self.conductor_api,
-                                security_groups=security_groups)
-        except Exception:
-            with excutils.save_and_reraise_exception():
-                LOG.exception(_('Instance failed network setup'),
-                              instance=instance)
 
-        LOG.debug(_('Instance network_info: |%s|'), network_info,
-                  instance=instance)
-
-        return network_info
+        def async_alloc():
+            LOG.debug(_("Allocating IP information in the background."),
+                      instance=instance)
+            try:
+                nwinfo = self.network_api.allocate_for_instance(
+                        context, instance, vpn=is_vpn,
+                        requested_networks=requested_networks,
+                        macs=macs,
+                        conductor_api=self.conductor_api,
+                        security_groups=security_groups)
+            except Exception:
+                with excutils.save_and_reraise_exception():
+                    LOG.exception(_('Instance failed network setup'),
+                                  instance=instance)
+            LOG.debug(_('Instance network_info: |%s|'), nwinfo,
+                      instance=instance)
+            return nwinfo
+        return network_model.NetworkInfoAsyncWrapper(async_alloc)
 
     def _prep_block_device(self, context, instance, bdms):
         """Set up the block device for an instance with error logging."""
diff --git a/nova/network/model.py b/nova/network/model.py
index cf01d98cf..240911ea9 100644
--- a/nova/network/model.py
+++ b/nova/network/model.py
@@ -15,6 +15,9 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import functools
+
+import eventlet
 import netaddr
 
 from nova import exception
@@ -434,3 +437,75 @@ class NetworkInfo(list):
 
             network_info.append((network_dict, info_dict))
         return network_info
+
+
+class NetworkInfoAsyncWrapper(NetworkInfo):
+    """Wrapper around NetworkInfo that allows retrieving NetworkInfo
+    in an async manner.
+
+    This allows one to start querying for network information before
+    you know you will need it.  If you have a long-running
+    operation, this allows the network model retrieval to occur in the
+    background.  When you need the data, it will ensure the async
+    operation has completed.
+
+    As an example:
+
+    def allocate_net_info(arg1, arg2)
+        return call_quantum_to_allocate(arg1, arg2)
+
+    network_info = NetworkInfoAsyncWrapper(allocate_net_info, arg1, arg2)
+    [do a long running operation -- real network_info will be retrieved
+    in the background]
+    [do something with network_info]
+    """
+
+    def __init__(self, async_method, *args, **kwargs):
+        self._gt = eventlet.spawn(async_method, *args, **kwargs)
+        methods = ['json', 'legacy', 'fixed_ips', 'floating_ips']
+        for method in methods:
+            fn = getattr(self, method)
+            wrapper = functools.partial(self._sync_wrapper, fn)
+            functools.update_wrapper(wrapper, fn)
+            setattr(self, method, wrapper)
+
+    def _sync_wrapper(self, wrapped, *args, **kwargs):
+        """Synchronize the model before running a method."""
+        self.wait()
+        return wrapped(*args, **kwargs)
+
+    def __getitem__(self, *args, **kwargs):
+        fn = super(NetworkInfoAsyncWrapper, self).__getitem__
+        return self._sync_wrapper(fn, *args, **kwargs)
+
+    def __iter__(self, *args, **kwargs):
+        fn = super(NetworkInfoAsyncWrapper, self).__iter__
+        return self._sync_wrapper(fn, *args, **kwargs)
+
+    def __len__(self, *args, **kwargs):
+        fn = super(NetworkInfoAsyncWrapper, self).__len__
+        return self._sync_wrapper(fn, *args, **kwargs)
+
+    def __str__(self, *args, **kwargs):
+        fn = super(NetworkInfoAsyncWrapper, self).__str__
+        return self._sync_wrapper(fn, *args, **kwargs)
+
+    def __repr__(self, *args, **kwargs):
+        fn = super(NetworkInfoAsyncWrapper, self).__repr__
+        return self._sync_wrapper(fn, *args, **kwargs)
+
+    def wait(self, do_raise=True):
+        """Wait for async call to finish."""
+        if self._gt is not None:
+            try:
+                # NOTE(comstud): This looks funky, but this object is
+                # subclassed from list.  In other words, 'self' is really
+                # just a list with a bunch of extra methods.  So this
+                # line just replaces the current list (which should be
+                # empty) with the result.
+                self[:] = self._gt.wait()
+            except Exception:
+                if do_raise:
+                    raise
+            finally:
+                self._gt = None
diff --git a/nova/tests/fake_network.py b/nova/tests/fake_network.py
index 42ce71ded..79af362bb 100644
--- a/nova/tests/fake_network.py
+++ b/nova/tests/fake_network.py
@@ -406,8 +406,11 @@ def set_stub_network_methods(stubs):
     def fake_networkinfo(*args, **kwargs):
         return network_model.NetworkInfo()
 
+    def fake_async_networkinfo(*args, **kwargs):
+        return network_model.NetworkInfoAsyncWrapper(fake_networkinfo)
+
     stubs.Set(cm, '_get_instance_nw_info', fake_networkinfo)
-    stubs.Set(cm, '_allocate_network', fake_networkinfo)
+    stubs.Set(cm, '_allocate_network', fake_async_networkinfo)
     stubs.Set(cm, '_deallocate_network', lambda *args, **kwargs: None)
 
 
diff --git a/nova/tests/network/test_network_info.py b/nova/tests/network/test_network_info.py
index 56522e6a5..bb3d91f55 100644
--- a/nova/tests/network/test_network_info.py
+++ b/nova/tests/network/test_network_info.py
@@ -332,6 +332,34 @@ class NetworkInfoTests(test.TestCase):
                  fake_network_cache_model.new_ip(
                     {'address': '10.10.0.3'})] * 4)
 
+    def test_create_async_model(self):
+        def async_wrapper():
+            return model.NetworkInfo(
+                    [fake_network_cache_model.new_vif(),
+                     fake_network_cache_model.new_vif(
+                            {'address': 'bb:bb:bb:bb:bb:bb'})])
+
+        ninfo = model.NetworkInfoAsyncWrapper(async_wrapper)
+        self.assertEqual(ninfo.fixed_ips(),
+                [fake_network_cache_model.new_ip({'address': '10.10.0.2'}),
+                 fake_network_cache_model.new_ip(
+                    {'address': '10.10.0.3'})] * 4)
+
+    def test_create_async_model_exceptions(self):
+        def async_wrapper():
+            raise test.TestingException()
+
+        ninfo = model.NetworkInfoAsyncWrapper(async_wrapper)
+        self.assertRaises(test.TestingException, ninfo.wait)
+        # 2nd one doesn't raise
+        self.assertEqual(None, ninfo.wait())
+        # Test that do_raise=False works on .wait()
+        ninfo = model.NetworkInfoAsyncWrapper(async_wrapper)
+        self.assertEqual(None, ninfo.wait(do_raise=False))
+        # Test we also raise calling a method
+        ninfo = model.NetworkInfoAsyncWrapper(async_wrapper)
+        self.assertRaises(test.TestingException, ninfo.fixed_ips)
+
     def test_get_floating_ips(self):
         vif = fake_network_cache_model.new_vif()
         vif['network']['subnets'][0]['ips'][0].add_floating_ip('192.168.1.1')